QuakeScout
Magnitude6.6

Reviewed by USGSAlaska93y ago

M6.6 earthquake 128 km SE of Chignik, Alaska

Saturday, July 28, 1934, 21:37:02 UTC · 55.625°N, 156.727°W

A magnitude 6.6 earthquake struck 128 km SE of Chignik, Alaska on Saturday, July 28, 1934, 21:37:02 UTC, at a depth of 20.0 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on May 4, 1923.

Magnitude
6.6
Strong · mw
Depth
20 km
Shallow
Felt reports
0
Did You Feel It?
Est. shaking
—
No ShakeMap
PAGER alert
None
Not issued
Tsunami
No flag
USGS feed

Outlined circle: this earthquake

In context

How big was it, and why here?

Energy released

138 kilotons of TNT

That is about 9 times the Hiroshima bomb. It released about 288 times the energy of a magnitude 5.0.

Tectonic setting

125 km

from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

20 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

Did You Feel It?

Where it was felt

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.

After the main event

Aftershocks within 100 km

USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 25 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 212 km W of this epicenter
  2. 7.14 km ENE of Karluk, AlaskaNovember 7, 1912 · 261 km NE of this epicenter
  3. 7.0113 km ESE of Chignik, AlaskaMay 4, 1923 · 24 km N of this epicenter
  4. 6.873 km SW of Sand Point, AlaskaJuly 2, 1922 · 299 km W of this epicenter
  5. 6.688 km SSE of Old Harbor, AlaskaDecember 21, 1917 · 258 km E of this epicenter
  6. 6.672 km SE of Sand Point, AlaskaOctober 16, 1932 · 198 km W of this epicenter
  7. 6.4103 km SSE of Akhiok, AlaskaDecember 28, 1917 · 225 km E of this epicenter
  8. 6.368 km SE of Sand Point, AlaskaOctober 30, 1932 · 198 km W of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 1900M8.3

    Kodiak Island

    9 Oct 1900 · 258 km away · intensity VIII

    Limited damage (under $1M)

  2. 1788M8.0

    Unga Island

    21 Jul 1788 · 276 km away · intensity VII

    Limited damage (under $1M)tsunami

  3. 1788M8.0

    Alaska Peninsula

    6 Aug 1788 · 279 km away

    tsunami

  4. 1906M7.6

    Aleutian Islands

    23 Dec 1906 · 221 km away

  5. 1912M7.5

    Alaska Peninsula

    7 Nov 1912 · 234 km away · intensity V

  6. 1868

    Alaska Peninsula

    15 May 1868 · 279 km away

    tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers

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